12F675 - wake up

championx · Joined: 28 Feb 2006 Posts: 151

Hi, im trying to wake up a 12F675 from sleep.

I have read the datasheet and it says that it cant wake up from Timer1 overflow.

I succesfully waked up from watchdog, but now im triyng to wake up from timer1.

I use the internal 4mhz oscillator.

Do somebody know how to configure the pic?

thanks!

temtronic · Posted: Mon Feb 14, 2011 6:43 am

Please post a small compilable test program,with compiler version.
It'll make it easier to diagnose.

championx · Joined: 28 Feb 2006 Posts: 151

I dont have a code, because i only need to know if i cant wake up the PIC using the timer1+internal_rc at 4mhz because i cant use an external oscillator, or a Clock IC.

I have a working program using the watchdog, but i need more accuracy.

thanks for your answer!

andrewg · Posted: Mon Feb 14, 2011 6:47 am

Are you sure you read the data sheet? Under Timer1 it says that it will wake up on overflow in asynchronous mode. It will have to be an external clock signal since the internal clock is off when asleep!
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Andrew

championx · Joined: 28 Feb 2006 Posts: 151

yes, i read the datasheet (im from argentina, so sometimes its a little dificcult to read english texts).

But, says that the internal oscillator will keep runing in sleep mode and says that you CAN put a external oscillator to run the timer1 during sleep. So i understand taht you use the internal rc, or if you wish, you CAN run it from an external oscillator.

Asyncronous mode its ONLY when you use an externa oscillator?

thanks for your help!

andrewg · Posted: Mon Feb 14, 2011 7:03 am

The internal oscillator is shutdown during sleep. You might have been confused by section "5.5" referring to an "oscillator circuit". Perhaps "oscillator driver" would have been a better choice of words.

What it's saying is that it will operate an external crystal up to 37kHz, which will provide an external clock source for timer 1.
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Andrew